The present invention relates to a curable and foamable organopolysiloxane composition or, more particularly, to an organopolysiloxane composition curable and simultaneously foamable into a cellular foamed silicone rubber having uniform distribution of the foam cells and high mechanical strengths and particularly useful as a material for sealing and filling in the building construction works. The invention also relates to a cured and foamed silicone rubber body obtained from the organopolysiloxane composition.
Known silicone rubber compositions in the prior art include those capable of foaming with simultaneous curing at room temperature or at a relatively low temperature above room temperature. Of the various types of foamable silicone rubber compositions, for example, Japanese patent publication Nos. 33-9297 and 44-8755 disclose a foamable composition in which foaming of the composition takes place with hydrogen gas as the foaming gas produced by the dehydrogenation reaction between an organopolysiloxane having hydrogen atoms directly bonded to the silicon atoms, referred to as the silicon-bonded hydrogen atoms hereinbelow, and an organosilane compound having a hydroxy group bonded directly to the silicon atom or a so-called organosilanol compound in the presence of a dehydrogenation catalyst such as quaternary ammonium salts, heavy metal carboxylates, alkali metal alkoxides and the like. Similar foamable compositions by use of a platinum catalyst are disclosed in Japanese patent publication Nos. 45-12675 and 52-42826 and Japanese patent Kokai No. 56-23462.
These foamable silicone rubber compositions in the prior art are practically not quite satisfactory as a material for sealing and filling in building construction works because of the relatively low mechanical strengths of the cured and foamed silicone rubber product obtained from the composition as well as poor uniformity in the distribution of the foam cells therein.